1. Field of the Invention
This invention pertains to apparatus for loading open top cases, and more particularly to apparatus for loading open top cases with complements of separate upright articles that are transported and guided to the cases along stationary guide loading tracks. More specifically, the invention relates to loading apparatus for bottles made from polyethylene terepthalate and called "pet bottles" in the trade.
2. Description of the Prior Art
Various equipment has been developed to automatically load open top cases with upright articles such as bottles and cans. Examples of prior case loading machines are discussed in U.S. Pat. Nos. 2,615,289; 3,194,382; 3,599,397; and 3,864,890.
An important part of a case loading machine is the means employed to handle the individual articles for proper insertion into a case. Prior handling and inserting means include electromagnetics, as illustrated in U.S. Pat. No. 3,194,382. The limitations of an electromagnetic handling system are readily apparent. A common means for handling and inserting individual articles consists of mechanical gripping devices of various designs. Typically, a gripper consists of a jaw-like mechanism adapted to grip the upper portion of the article, to insert the article into a case, and to release the articles at the proper time and location. U.S. Pat. Nos. 2,615,369; 2,783,869; and 3,864,890 are illustrative of the various gripping devices utilized for handling and inserting bottles. It will be appreciated that several problems are inherent with mechanical grippers. The grippers of necessity are assembled from numerous small parts. The resulting mechanism is therefore expensive, complicated and prone to malfunction. The jaws must exert a gripping force that is neither too weak nor too strong. The timing of the opening and closing of the jaws as they grip and release the articles is critical. The relative locations of the jaws and articles must be very carefully controlled for proper gripping operation. None of the prior art techniques have been found suitable for loading the new pet plastic soft drink bottles having a pronounced neck flange.